A plasma display panel (hereinafter referred to as a PDP or simply a panel) is a display device with excellent visibility, large screen, and low-profile, lightweight body. The difference in discharging divides PDPs into two types of the alternating current (AC) type and the direct current (DC) type. In terms of the structure of electrodes, the PDPs fall into the 3-electrode surface discharge type and the opposing discharge type. In recent years, the dominating PDP is the AC type 3-electrode surface discharge PDP by virtue of having higher resolution and easier fabrication.
Generally, the AC type 3-electrode surface discharge PDP contains a front substrate and a back substrate oppositely disposed from each other, and a plurality of discharge cells therebetween. On a front glass plate of the front substrate, scan electrodes and sustain electrodes as display electrodes are arranged in parallel with each other, and over which, a dielectric layer and a protecting layer are formed to cover the display electrodes. On the other hand, on a back glass plate of the back substrate, data electrodes are disposed in a parallel arrangement, and over which, a dielectric layer is formed to cover the electrodes. On the dielectric layer between the data electrodes, a plurality of barrier ribs is formed in parallel with the rows of the data electrodes. Furthermore, a phosphor layer is formed between the barrier ribs and on the surface of the dielectric layer. The front substrate and the rear substrate are sealed with each other so that the display electrodes are orthogonal to the data electrodes in the narrow space between the two substrates. The narrow space, i.e., the discharge space, is filled with discharge gas. The panel is thus fabricated.
Such a panel just finished, however, generally exhibits a high voltage at the start of discharging, and the discharge itself is in an unstable condition. The panel is therefore aged in the manufacturing process to obtain consistent and stable discharge characteristics.
Conventionally, a method—in which an anti-phased rectangular wave, that is, voltage having an alternate voltage component, is placed between the display electrodes, i.e., a scan electrode and a sustain electrode, for a long period of time—has been employed for aging panels. To shorten the aging time, some methods have been suggested. For example, Japanese Patent Non-Examined Publication No. H07-226162 introduces the method in which a rectangular wave is applied, via an inductor, to the electrodes of a panel. On the other hand, Japanese Patent Non-Examined Publication No. 2002-231141 suggests the method as a combination of two kinds of discharging. According to the method, pulse voltage having different polarity is placed between a scan electrode and a sustain electrode (i.e., discharging in the same surface) and consecutively, pulse voltage having different polarity is now placed between the display electrodes and the data electrodes (i.e., discharging between the opposite surfaces).
Even employing the methods above, the aging time still takes about 10 hours before obtaining a stabilized discharging. The long aging time inevitably increases power consumption in the aging process, which has been a leading cause of increasing the running cost of manufacturing PDPs. Besides, the time-consuming aging process has caused problems: the factory space for keeping the panels for the aging process, and environmental conditions, such as air-conditioning, for properly maintaining the panels through the manufacturing process. From now on, further increase in manufacturing volumes and screen-sizes of the PDP apparently encourages the problems above and invites serious conditions.
The present invention addresses the problems above. It is therefore an object of the invention to provide an improved method of aging panels, allowing the aging time to be significantly reduced with an efficient use of electric power.